Sharif Digital Repository

Most investigations showed that the prevalent thermodynamic models are incapable of predicting asphaltene precipitation without extensive data fitting. This is primarily due to lack of knowledge of the asphaltene properties, its complex nature and the large number of parameters affecting precipitation. Hece, several authors tried to generate a simple and universe mathematical model in order to predict the amount of asphaltene precipitation. In spite of these efforts, the authors only considered temperature and type of solvents as the effective parameters in generating their scaling equations. The major disadvantage of these models is their inability in predicting the amount of asphaltene... 

Drought is one of the most serious hazards that has more effect on human societies than the others. Scentific researches have important roles in drought planning and management of water resources, especially in time of crisis and predicted big event by the event that the crisis management turnover. The main objective of this research is to develop an approach to analyze the spatial patterns of meteorological droughts based on annual precipitation data in Iran. By using a nonparametric spatial analysis neural network algorithm, the normalized and standardized precipitation data are classified into certain degrees of drought severity (extreme drought, severe drought, mild drought, and...